1. Field of the Invention
This invention relates to an improved method of coal liquefaction and resid upgrading. More particularly, this invention relates to the use of lignin in coal liquefaction and resid upgrading.
2. Description of Prior Art
In the last two decades there has been a resurgence of interest in coal as a source of synthetic crude oil. Accordingly, the art relating to the liquefaction of coal has developed significantly in the last two decades. However, most of the art relating to coal liquefaction relates to optimizing coal liquefaction processes from an engineering point of view. Until recently, optimization of coal liquefaction and other coal chemistry has not been approached as extensively from a chemical point of view.
Coal liquefaction processes are predicated on controlled heating of coal in the absence of oxygen to convert coal into liquid hydrocarbons, gas and ash. Some processes use an H-donor solvent to solubilize the coal at elevated temperatures. Typical H-donor solvents are aromatic compounds, e.g., phenanthrene, dihydrophenanthrene and tetralins. Optionally, a liquefaction catalyst, e.g., cobalt molybdate, may also be added to accelerate the liquefaction process. Some prior art processes (e.g., Chen et al, U.S. Pat. No. 4,247,384) combine coal with other carbonaceous materials, e.g., wood, cellulose, plants and/or peat. However, in such prior art processes the use of carbonaceous materials other than coal appears to be incidental to the process and the relative proportions of coal and other materials are not specified. Similarly, Pyzel, British Pat. No. 173,907, discloses a process for distilling bituminous materials optionally mixed with other solids, e.g., sand, sawdust, powdered coal. This process appears to be dissimilar from a coal liquefaction process. Pyzel simply distills the starting material to obtain oils, gas and coke. Relative proportions of coal and the other solids are not specified.